/*
 * jQuery UI Datepicker
 *
 * Copyright (c) 2006, 2007, 2008 Marc Grabanski
 * Dual licensed under the MIT (MIT-LICENSE.txt)
 * and GPL (GPL-LICENSE.txt) licenses.
 *
 * http://docs.jquery.com/UI/Datepicker
 *
 * Depends:
 *	ui.core.js
 *
 * Marc Grabanski (m@marcgrabanski.com) and Keith Wood (kbwood@virginbroadband.com.au).
 */

(function($) { // hide the namespace

    var PROP_NAME = 'datepicker';

    /* Date picker manager.
     Use the singleton instance of this class, $.datepicker, to interact with the date picker.
     Settings for (groups of) date pickers are maintained in an instance object,
     allowing multiple different settings on the same page. */

    function Datepicker() {
        this.debug = false; // Change this to true to start debugging
        this._curInst = null; // The current instance in use
        this._disabledInputs = []; // List of date picker inputs that have been disabled
        this._datepickerShowing = false; // True if the popup picker is showing , false if not
        this._inDialog = false; // True if showing within a "dialog", false if not
        this._mainDivId = 'ui-datepicker-div'; // The ID of the main datepicker division
        this._appendClass = 'ui-datepicker-append'; // The name of the append marker class
        this._triggerClass = 'ui-datepicker-trigger'; // The name of the trigger marker class
        this._dialogClass = 'ui-datepicker-dialog'; // The name of the dialog marker class
        this._promptClass = 'ui-datepicker-prompt'; // The name of the dialog prompt marker class
        this._unselectableClass = 'ui-datepicker-unselectable'; // The name of the unselectable cell marker class
        this._currentClass = 'ui-datepicker-current-day'; // The name of the current day marker class
        this.regional = []; // Available regional settings, indexed by language code
        this.regional[''] = { // Default regional settings
            clearText: '清除', // Display text for clear link
            clearStatus: '清除时间', // Status text for clear link
            closeText: '关闭', // Display text for close link
            closeStatus: '关闭选择框', // Status text for close link
            prevText: '上一月', // Display text for previous month link
            prevStatus: '显示上一月日期列表', // Status text for previous month link
            nextText: '下一月', // Display text for next month link
            nextStatus: '显示下一月日期列表', // Status text for next month link
            currentText: '今天', // Display text for current month link
            currentStatus: '查看当月日期列表', // Status text for current month link
            monthNames: ['一月','二月','三月','四月','五月','六月',
                '七月','八月','九月','十月','十一月','十二月'], // Names of months for drop-down and formatting
            monthNamesShort: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'], // For formatting
            monthStatus: 'Show a different month', // Status text for selecting a month
            yearStatus: 'Show a different year', // Status text for selecting a year
            weekHeader: 'Wk', // Header for the week of the year column
            weekStatus: 'Week of the year', // Status text for the week of the year column
            dayNames: ['周日', '周一', '周二', '周三', '周四', '周五', '周六'], // For formatting
            dayNamesShort: ['日', '一', '二', '三', '四', '五', '六'], // For formatting
            dayNamesMin: ['日','一','二','三','四','五','六'], // Column headings for days starting at Sunday
            dayStatus: 'Set DD as first week day', // Status text for the day of the week selection
            dateStatus: 'Select DD, M d', // Status text for the date selection
            dateFormat: 'mm/dd/yy', // See format options on parseDate
            firstDay: 0, // The first day of the week, Sun = 0, Mon = 1, ...
            initStatus: 'Select a date', // Initial Status text on opening
            isRTL: false // True if right-to-left language, false if left-to-right
        };
        this._defaults = { // Global defaults for all the date picker instances
            showOn: 'focus', // 'focus' for popup on focus,
            // 'button' for trigger button, or 'both' for either
            showAnim: 'show', // Name of jQuery animation for popup
            showOptions: {}, // Options for enhanced animations
            defaultDate: null, // Used when field is blank: actual date,
            // +/-number for offset from today, null for today
            appendText: '', // Display text following the input box, e.g. showing the format
            buttonText: '...', // Text for trigger button
            buttonImage: '', // URL for trigger button image
            buttonImageOnly: false, // True if the image appears alone, false if it appears on a button
            closeAtTop: true, // True to have the clear/close at the top,
            // false to have them at the bottom
            mandatory: false, // True to hide the Clear link, false to include it
            hideIfNoPrevNext: false, // True to hide next/previous month links
            // if not applicable, false to just disable them
            navigationAsDateFormat: false, // True if date formatting applied to prev/today/next links
            gotoCurrent: false, // True if today link goes back to current selection instead
            changeMonth: true, // True if month can be selected directly, false if only prev/next
            changeYear: true, // True if year can be selected directly, false if only prev/next
            yearRange: '-10:+10', // Range of years to display in drop-down,
            // either relative to current year (-nn:+nn) or absolute (nnnn:nnnn)
            changeFirstDay: true, // True to click on day name to change, false to remain as set
            highlightWeek: false, // True to highlight the selected week
            showOtherMonths: false, // True to show dates in other months, false to leave blank
            showWeeks: false, // True to show week of the year, false to omit
            calculateWeek: this.iso8601Week, // How to calculate the week of the year,
            // takes a Date and returns the number of the week for it
            shortYearCutoff: '+10', // Short year values < this are in the current century,
            // > this are in the previous century,
            // string value starting with '+' for current year + value
            showStatus: false, // True to show status bar at bottom, false to not show it
            statusForDate: this.dateStatus, // Function to provide status text for a date -
            // takes date and instance as parameters, returns display text
            minDate: null, // The earliest selectable date, or null for no limit
            maxDate: null, // The latest selectable date, or null for no limit
            duration: 'normal', // Duration of display/closure
            beforeShowDay: null, // Function that takes a date and returns an array with
            // [0] = true if selectable, false if not, [1] = custom CSS class name(s) or '',
            // [2] = cell title (optional), e.g. $.datepicker.noWeekends
            beforeShow: null, // Function that takes an input field and
            // returns a set of custom settings for the date picker
            onSelect: null, // Define a callback function when a date is selected
            onChangeMonthYear: null, // Define a callback function when the month or year is changed
            onClose: null, // Define a callback function when the datepicker is closed
            numberOfMonths: 1, // Number of months to show at a time
            stepMonths: 1, // Number of months to step back/forward
            rangeSelect: false, // Allows for selecting a date range on one date picker
            rangeSeparator: ' - ', // Text between two dates in a range
            altField: '', // Selector for an alternate field to store selected dates into
            altFormat: '' // The date format to use for the alternate field
        };
        $.extend(this._defaults, this.regional['']);
        this.dpDiv = $('<div id="' + this._mainDivId + '" style="display: none;"></div>');
    }

    $.extend(Datepicker.prototype, {
        /* Class name added to elements to indicate already configured with a date picker. */
        markerClassName: 'hasDatepicker',

        /* Debug logging (if enabled). */
        log: function () {
            if (this.debug)
                console.log.apply('', arguments);
        },

        /* Override the default settings for all instances of the date picker.
         @param  settings  object - the new settings to use as defaults (anonymous object)
         @return the manager object */
        setDefaults: function(settings) {
            extendRemove(this._defaults, settings || {});
            return this;
        },

        /* Attach the date picker to a jQuery selection.
         @param  target    element - the target input field or division or span
         @param  settings  object - the new settings to use for this date picker instance (anonymous) */
        _attachDatepicker: function(target, settings) {
            // check for settings on the control itself - in namespace 'date:'
            var inlineSettings = null;
            for (attrName in this._defaults) {
                var attrValue = target.getAttribute('date:' + attrName);
                if (attrValue) {
                    inlineSettings = inlineSettings || {};
                    try {
                        inlineSettings[attrName] = eval(attrValue);
                    } catch (err) {
                        inlineSettings[attrName] = attrValue;
                    }
                }
            }
            var nodeName = target.nodeName.toLowerCase();
            var inline = (nodeName == 'div' || nodeName == 'span');
            if (!target.id)
                target.id = 'dp' + new Date().getTime();
            var inst = this._newInst($(target), inline);
            inst.settings = $.extend({}, settings || {}, inlineSettings || {});
            if (nodeName == 'input') {
                this._connectDatepicker(target, inst);
            } else if (inline) {
                this._inlineDatepicker(target, inst);
            }
        },

        /* Create a new instance object. */
        _newInst: function(target, inline) {
            return {id: target[0].id, input: target, // associated target
                selectedDay: 0, selectedMonth: 0, selectedYear: 0, // current selection
                drawMonth: 0, drawYear: 0, // month being drawn
                inline: inline, // is datepicker inline or not
                dpDiv: (!inline ? this.dpDiv : // presentation div
                        $('<div class="ui-datepicker-inline"></div>'))};
        },

        /* Attach the date picker to an input field. */
        _connectDatepicker: function(target, inst) {
            var input = $(target);
            if (input.hasClass(this.markerClassName))
                return;
            var appendText = this._get(inst, 'appendText');
            var isRTL = this._get(inst, 'isRTL');
            if (appendText)
                input[isRTL ? 'before' : 'after']('<span class="' + this._appendClass + '">' + appendText + '</span>');
            var showOn = this._get(inst, 'showOn');
            if (showOn == 'focus' || showOn == 'both') // pop-up date picker when in the marked field
                input.focus(this._showDatepicker);
            if (showOn == 'button' || showOn == 'both') { // pop-up date picker when button clicked
                var buttonText = this._get(inst, 'buttonText');
                var buttonImage = this._get(inst, 'buttonImage');
                var trigger = $(this._get(inst, 'buttonImageOnly') ?
                                $('<img/>').addClass(this._triggerClass).
                                        attr({ src: buttonImage, alt: buttonText, title: buttonText }) :
                                $('<button type="button"></button>').addClass(this._triggerClass).
                                        html(buttonImage == '' ? buttonText : $('<img/>').attr(
                                { src:buttonImage, alt:buttonText, title:buttonText })));
                input[isRTL ? 'before' : 'after'](trigger);
                trigger.click(function() {
                    if ($.datepicker._datepickerShowing && $.datepicker._lastInput == target)
                        $.datepicker._hideDatepicker();
                    else
                        $.datepicker._showDatepicker(target);
                    return false;
                });
            }
            input.addClass(this.markerClassName).keydown(this._doKeyDown).keypress(this._doKeyPress).
                    bind("setData.datepicker", function(event, key, value) {
                inst.settings[key] = value;
            }).bind("getData.datepicker", function(event, key) {
                return this._get(inst, key);
            });
            $.data(target, PROP_NAME, inst);
        },

        /* Attach an inline date picker to a div. */
        _inlineDatepicker: function(target, inst) {
            var input = $(target);
            if (input.hasClass(this.markerClassName))
                return;
            input.addClass(this.markerClassName).append(inst.dpDiv).
                    bind("setData.datepicker", function(event, key, value) {
                inst.settings[key] = value;
            }).bind("getData.datepicker", function(event, key) {
                return this._get(inst, key);
            });
            $.data(target, PROP_NAME, inst);
            this._setDate(inst, this._getDefaultDate(inst));
            this._updateDatepicker(inst);
        },

        /* Pop-up the date picker in a "dialog" box.
         @param  input     element - ignored
         @param  dateText  string - the initial date to display (in the current format)
         @param  onSelect  function - the function(dateText) to call when a date is selected
         @param  settings  object - update the dialog date picker instance's settings (anonymous object)
         @param  pos       int[2] - coordinates for the dialog's position within the screen or
         event - with x/y coordinates or
         leave empty for default (screen centre)
         @return the manager object */
        _dialogDatepicker: function(input, dateText, onSelect, settings, pos) {
            var inst = this._dialogInst; // internal instance
            if (!inst) {
                var id = 'dp' + new Date().getTime();
                this._dialogInput = $('<input type="text" id="' + id +
                                      '" size="1" style="position: absolute; top: -100px;"/>');
                this._dialogInput.keydown(this._doKeyDown);
                $('body').append(this._dialogInput);
                inst = this._dialogInst = this._newInst(this._dialogInput, false);
                inst.settings = {};
                $.data(this._dialogInput[0], PROP_NAME, inst);
            }
            extendRemove(inst.settings, settings || {});
            this._dialogInput.val(dateText);

            this._pos = (pos ? (pos.length ? pos : [pos.pageX, pos.pageY]) : null);
            if (!this._pos) {
                var browserWidth = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;
                var browserHeight = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
                var scrollX = document.documentElement.scrollLeft || document.body.scrollLeft;
                var scrollY = document.documentElement.scrollTop || document.body.scrollTop;
                this._pos = // should use actual width/height below
                [(browserWidth / 2) - 100 + scrollX, (browserHeight / 2) - 150 + scrollY];
            }

            // move input on screen for focus, but hidden behind dialog
            this._dialogInput.css('left', this._pos[0] + 'px').css('top', this._pos[1] + 'px');
            inst.settings.onSelect = onSelect;
            this._inDialog = true;
            this.dpDiv.addClass(this._dialogClass);
            this._showDatepicker(this._dialogInput[0]);
            if ($.blockUI)
                $.blockUI(this.dpDiv);
            $.data(this._dialogInput[0], PROP_NAME, inst);
            return this;
        },

        /* Detach a datepicker from its control.
         @param  target    element - the target input field or division or span */
        _destroyDatepicker: function(target) {
            var nodeName = target.nodeName.toLowerCase();
            var $target = $(target);
            $.removeData(target, PROP_NAME);
            if (nodeName == 'input') {
                $target.siblings('.' + this._appendClass).remove().end().
                        siblings('.' + this._triggerClass).remove().end().
                        removeClass(this.markerClassName).
                        unbind('focus', this._showDatepicker).
                        unbind('keydown', this._doKeyDown).
                        unbind('keypress', this._doKeyPress);
            } else if (nodeName == 'div' || nodeName == 'span')
                $target.removeClass(this.markerClassName).empty();
        },

        /* Enable the date picker to a jQuery selection.
         @param  target    element - the target input field or division or span */
        _enableDatepicker: function(target) {
            target.disabled = false;
            $(target).siblings('button.' + this._triggerClass).each(function() {
                this.disabled = false;
            }).end().
                    siblings('img.' + this._triggerClass).css({opacity: '1.0', cursor: ''});
            this._disabledInputs = $.map(this._disabledInputs,
                    function(value) {
                        return (value == target ? null : value);
                    }); // delete entry
        },

        /* Disable the date picker to a jQuery selection.
         @param  target    element - the target input field or division or span */
        _disableDatepicker: function(target) {
            target.disabled = true;
            $(target).siblings('button.' + this._triggerClass).each(function() {
                this.disabled = true;
            }).end().
                    siblings('img.' + this._triggerClass).css({opacity: '0.5', cursor: 'default'});
            this._disabledInputs = $.map(this._disabledInputs,
                    function(value) {
                        return (value == target ? null : value);
                    }); // delete entry
            this._disabledInputs[this._disabledInputs.length] = target;
        },

        /* Is the first field in a jQuery collection disabled as a datepicker?
         @param  target    element - the target input field or division or span
         @return boolean - true if disabled, false if enabled */
        _isDisabledDatepicker: function(target) {
            if (!target)
                return false;
            for (var i = 0; i < this._disabledInputs.length; i++) {
                if (this._disabledInputs[i] == target)
                    return true;
            }
            return false;
        },

        /* Update the settings for a date picker attached to an input field or division.
         @param  target  element - the target input field or division or span
         @param  name    object - the new settings to update or
         string - the name of the setting to change or
         @param  value   any - the new value for the setting (omit if above is an object) */
        _changeDatepicker: function(target, name, value) {
            var settings = name || {};
            if (typeof name == 'string') {
                settings = {};
                settings[name] = value;
            }
            if (inst = $.data(target, PROP_NAME)) {
                extendRemove(inst.settings, settings);
                this._updateDatepicker(inst);
            }
        },

        /* Set the dates for a jQuery selection.
         @param  target   element - the target input field or division or span
         @param  date     Date - the new date
         @param  endDate  Date - the new end date for a range (optional) */
        _setDateDatepicker: function(target, date, endDate) {
            var inst = $.data(target, PROP_NAME);
            if (inst) {
                this._setDate(inst, date, endDate);
                this._updateDatepicker(inst);
            }
        },

        /* Get the date(s) for the first entry in a jQuery selection.
         @param  target  element - the target input field or division or span
         @return Date - the current date or
         Date[2] - the current dates for a range */
        _getDateDatepicker: function(target) {
            var inst = $.data(target, PROP_NAME);
            if (inst)
                this._setDateFromField(inst);
            return (inst ? this._getDate(inst) : null);
        },

        /* Handle keystrokes. */
        _doKeyDown: function(e) {
            var inst = $.data(e.target, PROP_NAME);
            var handled = true;
            if ($.datepicker._datepickerShowing)
                switch (e.keyCode) {
                    case 9:  $.datepicker._hideDatepicker(null, '');
                        break; // hide on tab out
                    case 13: $.datepicker._selectDay(e.target, inst.selectedMonth, inst.selectedYear,
                            $('td.ui-datepicker-days-cell-over', inst.dpDiv)[0]);
                        return false; // don't submit the form
                        break; // select the value on enter
                    case 27: $.datepicker._hideDatepicker(null, $.datepicker._get(inst, 'duration'));
                        break; // hide on escape
                    case 33: $.datepicker._adjustDate(e.target, (e.ctrlKey ? -1 :
                                                                 -$.datepicker._get(inst, 'stepMonths')), (e.ctrlKey ? 'Y' : 'M'));
                        break; // previous month/year on page up/+ ctrl
                    case 34: $.datepicker._adjustDate(e.target, (e.ctrlKey ? +1 :
                                                                 +$.datepicker._get(inst, 'stepMonths')), (e.ctrlKey ? 'Y' : 'M'));
                        break; // next month/year on page down/+ ctrl
                    case 35: if (e.ctrlKey) $.datepicker._clearDate(e.target);
                        break; // clear on ctrl+end
                    case 36: if (e.ctrlKey) $.datepicker._gotoToday(e.target);
                        break; // current on ctrl+home
                    case 37: if (e.ctrlKey) $.datepicker._adjustDate(e.target, -1, 'D');
                        break; // -1 day on ctrl+left
                    case 38: if (e.ctrlKey) $.datepicker._adjustDate(e.target, -7, 'D');
                        break; // -1 week on ctrl+up
                    case 39: if (e.ctrlKey) $.datepicker._adjustDate(e.target, +1, 'D');
                        break; // +1 day on ctrl+right
                    case 40: if (e.ctrlKey) $.datepicker._adjustDate(e.target, +7, 'D');
                        break; // +1 week on ctrl+down
                    default: handled = false;
                }
            else if (e.keyCode == 36 && e.ctrlKey) // display the date picker on ctrl+home
                $.datepicker._showDatepicker(this);
            else
                handled = false;
            if (handled) {
                e.preventDefault();
                e.stopPropagation();
            }
        },

        /* Filter entered characters - based on date format. */
        _doKeyPress: function(e) {
            var inst = $.data(e.target, PROP_NAME);
            var chars = $.datepicker._possibleChars($.datepicker._get(inst, 'dateFormat'));
            var chr = String.fromCharCode(e.charCode == undefined ? e.keyCode : e.charCode);
            return e.ctrlKey || (chr < ' ' || !chars || chars.indexOf(chr) > -1);
        },

        /* Pop-up the date picker for a given input field.
         @param  input  element - the input field attached to the date picker or
         event - if triggered by focus */
        _showDatepicker: function(input) {
            input = input.target || input;
            if (input.nodeName.toLowerCase() != 'input') // find from button/image trigger
                input = $('input', input.parentNode)[0];
            if ($.datepicker._isDisabledDatepicker(input) || $.datepicker._lastInput == input) // already here
                return;
            var inst = $.data(input, PROP_NAME);
            var beforeShow = $.datepicker._get(inst, 'beforeShow');
            extendRemove(inst.settings, (beforeShow ? beforeShow.apply(input, [input, inst]) : {}));
            $.datepicker._hideDatepicker(null, '');
            $.datepicker._lastInput = input;
            $.datepicker._setDateFromField(inst);
            if ($.datepicker._inDialog) // hide cursor
                input.value = '';
            if (!$.datepicker._pos) { // position below input
                $.datepicker._pos = $.datepicker._findPos(input);
                $.datepicker._pos[1] += input.offsetHeight; // add the height
            }
            var isFixed = false;
            $(input).parents().each(function() {
                isFixed |= $(this).css('position') == 'fixed';
                return !isFixed;
            });
            if (isFixed && $.browser.opera) { // correction for Opera when fixed and scrolled
                $.datepicker._pos[0] -= document.documentElement.scrollLeft;
                $.datepicker._pos[1] -= document.documentElement.scrollTop;
            }
            var offset = {left: $.datepicker._pos[0], top: $.datepicker._pos[1]};
            $.datepicker._pos = null;
            inst.rangeStart = null;
            // determine sizing offscreen
            inst.dpDiv.css({position: 'absolute', display: 'block', top: '-1000px'});
            $.datepicker._updateDatepicker(inst);
            // fix width for dynamic number of date pickers
            inst.dpDiv.width($.datepicker._getNumberOfMonths(inst)[1] *
                             $('.ui-datepicker', inst.dpDiv[0])[0].offsetWidth);
            // and adjust position before showing
            offset = $.datepicker._checkOffset(inst, offset, isFixed);
            inst.dpDiv.css({position: ($.datepicker._inDialog && $.blockUI ?
                                       'static' : (isFixed ? 'fixed' : 'absolute')), display: 'none',
                left: offset.left + 'px', top: offset.top + 'px'});
            if (!inst.inline) {
                var showAnim = $.datepicker._get(inst, 'showAnim') || 'show';
                var duration = $.datepicker._get(inst, 'duration');
                var postProcess = function() {
                    $.datepicker._datepickerShowing = true;
                    if ($.browser.msie && parseInt($.browser.version) < 7) // fix IE < 7 select problems
                        $('iframe.ui-datepicker-cover').css({width: inst.dpDiv.width() + 4,
                            height: inst.dpDiv.height() + 4});
                };
                if ($.effects && $.effects[showAnim])
                    inst.dpDiv.show(showAnim, $.datepicker._get(inst, 'showOptions'), duration, postProcess);
                else
                    inst.dpDiv[showAnim](duration, postProcess);
                if (duration == '')
                    postProcess();
                if (inst.input[0].type != 'hidden')
                    inst.input[0].focus();
                $.datepicker._curInst = inst;
            }
        },

        /* Generate the date picker content. */
        _updateDatepicker: function(inst) {
            var dims = {width: inst.dpDiv.width() + 4,
                height: inst.dpDiv.height() + 4};
            inst.dpDiv.empty().append(this._generateDatepicker(inst)).
                    find('iframe.ui-datepicker-cover').
                    css({width: dims.width, height: dims.height});
            var numMonths = this._getNumberOfMonths(inst);
            inst.dpDiv[(numMonths[0] != 1 || numMonths[1] != 1 ? 'add' : 'remove') +
                       'Class']('ui-datepicker-multi');
            inst.dpDiv[(this._get(inst, 'isRTL') ? 'add' : 'remove') +
                       'Class']('ui-datepicker-rtl');
            if (inst.input && inst.input[0].type != 'hidden')
                $(inst.input[0]).focus();
        },

        /* Check positioning to remain on screen. */
        _checkOffset: function(inst, offset, isFixed) {
            var pos = inst.input ? this._findPos(inst.input[0]) : null;
            var browserWidth = window.innerWidth || document.documentElement.clientWidth;
            var browserHeight = window.innerHeight || document.documentElement.clientHeight;
            var scrollX = document.documentElement.scrollLeft || document.body.scrollLeft;
            var scrollY = document.documentElement.scrollTop || document.body.scrollTop;
            // reposition date picker horizontally if outside the browser window
            if (this._get(inst, 'isRTL') || (offset.left + inst.dpDiv.width() - scrollX) > browserWidth)
                offset.left = Math.max((isFixed ? 0 : scrollX),
                        pos[0] + (inst.input ? inst.input.width() : 0) - (isFixed ? scrollX : 0) - inst.dpDiv.width() -
                        (isFixed && $.browser.opera ? document.documentElement.scrollLeft : 0));
            else
                offset.left -= (isFixed ? scrollX : 0);
            // reposition date picker vertically if outside the browser window
            if ((offset.top + inst.dpDiv.height() - scrollY) > browserHeight)
                offset.top = Math.max((isFixed ? 0 : scrollY),
                        pos[1] - (isFixed ? scrollY : 0) - (this._inDialog ? 0 : inst.dpDiv.height()) -
                        (isFixed && $.browser.opera ? document.documentElement.scrollTop : 0));
            else
                offset.top -= (isFixed ? scrollY : 0);
            return offset;
        },

        /* Find an object's position on the screen. */
        _findPos: function(obj) {
            while (obj && (obj.type == 'hidden' || obj.nodeType != 1)) {
                obj = obj.nextSibling;
            }
            var position = $(obj).offset();
            return [position.left, position.top];
        },

        /* Hide the date picker from view.
         @param  input  element - the input field attached to the date picker
         @param  duration  string - the duration over which to close the date picker */
        _hideDatepicker: function(input, duration) {
            var inst = this._curInst;
            if (!inst)
                return;
            var rangeSelect = this._get(inst, 'rangeSelect');
            if (rangeSelect && this._stayOpen)
                this._selectDate('#' + inst.id, this._formatDate(inst,
                        inst.currentDay, inst.currentMonth, inst.currentYear));
            this._stayOpen = false;
            if (this._datepickerShowing) {
                duration = (duration != null ? duration : this._get(inst, 'duration'));
                var showAnim = this._get(inst, 'showAnim');
                var postProcess = function() {
                    $.datepicker._tidyDialog(inst);
                };
                if (duration != '' && $.effects && $.effects[showAnim])
                    inst.dpDiv.hide(showAnim, $.datepicker._get(inst, 'showOptions'),
                            duration, postProcess);
                else
                    inst.dpDiv[(duration == '' ? 'hide' : (showAnim == 'slideDown' ? 'slideUp' :
                                                           (showAnim == 'fadeIn' ? 'fadeOut' : 'hide')))](duration, postProcess);
                if (duration == '')
                    this._tidyDialog(inst);
                var onClose = this._get(inst, 'onClose');
                if (onClose)
                    onClose.apply((inst.input ? inst.input[0] : null),
                            [this._getDate(inst), inst]);  // trigger custom callback
                this._datepickerShowing = false;
                this._lastInput = null;
                inst.settings.prompt = null;
                if (this._inDialog) {
                    this._dialogInput.css({ position: 'absolute', left: '0', top: '-100px' });
                    if ($.blockUI) {
                        $.unblockUI();
                        $('body').append(this.dpDiv);
                    }
                }
                this._inDialog = false;
            }
            this._curInst = null;
        },

        /* Tidy up after a dialog display. */
        _tidyDialog: function(inst) {
            inst.dpDiv.removeClass(this._dialogClass).unbind('.ui-datepicker');
            $('.' + this._promptClass, inst.dpDiv).remove();
        },

        /* Close date picker if clicked elsewhere. */
        _checkExternalClick: function(event) {
            if (!$.datepicker._curInst)
                return;
            var $target = $(event.target);
            if (($target.parents('#' + $.datepicker._mainDivId).length == 0) &&
                !$target.hasClass($.datepicker.markerClassName) &&
                !$target.hasClass($.datepicker._triggerClass) &&
                $.datepicker._datepickerShowing && !($.datepicker._inDialog && $.blockUI))
                $.datepicker._hideDatepicker(null, '');
        },

        /* Adjust one of the date sub-fields. */
        _adjustDate: function(id, offset, period) {
            var target = $(id);
            var inst = $.data(target[0], PROP_NAME);
            this._adjustInstDate(inst, offset, period);
            this._updateDatepicker(inst);
        },

        /* Action for current link. */
        _gotoToday: function(id) {
            var target = $(id);
            var inst = $.data(target[0], PROP_NAME);
            if (this._get(inst, 'gotoCurrent') && inst.currentDay) {
                inst.selectedDay = inst.currentDay;
                inst.drawMonth = inst.selectedMonth = inst.currentMonth;
                inst.drawYear = inst.selectedYear = inst.currentYear;
            }
            else {
                var date = new Date();
                inst.selectedDay = date.getDate();
                inst.drawMonth = inst.selectedMonth = date.getMonth();
                inst.drawYear = inst.selectedYear = date.getFullYear();
            }
            this._adjustDate(target);
            this._notifyChange(inst);
        },

        /* Action for selecting a new month/year. */
        _selectMonthYear: function(id, select, period) {
            var target = $(id);
            var inst = $.data(target[0], PROP_NAME);
            inst._selectingMonthYear = false;
            inst[period == 'M' ? 'drawMonth' : 'drawYear'] =
            select.options[select.selectedIndex].value - 0;
            this._adjustDate(target);
            this._notifyChange(inst);
        },

        /* Restore input focus after not changing month/year. */
        _clickMonthYear: function(id) {
            var target = $(id);
            var inst = $.data(target[0], PROP_NAME);
            if (inst.input && inst._selectingMonthYear && !$.browser.msie)
                inst.input[0].focus();
            inst._selectingMonthYear = !inst._selectingMonthYear;
        },

        /* Action for changing the first week day. */
        _changeFirstDay: function(id, day) {
            var target = $(id);
            var inst = $.data(target[0], PROP_NAME);
            inst.settings.firstDay = day;
            this._updateDatepicker(inst);
        },

        /* Action for selecting a day. */
        _selectDay: function(id, month, year, td) {
            if ($(td).hasClass(this._unselectableClass))
                return;
            var target = $(id);
            var inst = $.data(target[0], PROP_NAME);
            var rangeSelect = this._get(inst, 'rangeSelect');
            if (rangeSelect) {
                this._stayOpen = !this._stayOpen;
                if (this._stayOpen) {
                    $('.ui-datepicker td').removeClass(this._currentClass);
                    $(td).addClass(this._currentClass);
                }
            }
            inst.selectedDay = inst.currentDay = $('a', td).html();
            inst.selectedMonth = inst.currentMonth = month;
            inst.selectedYear = inst.currentYear = year;
            if (this._stayOpen) {
                inst.endDay = inst.endMonth = inst.endYear = null;
            }
            else if (rangeSelect) {
                inst.endDay = inst.currentDay;
                inst.endMonth = inst.currentMonth;
                inst.endYear = inst.currentYear;
            }
            this._selectDate(id, this._formatDate(inst,
                    inst.currentDay, inst.currentMonth, inst.currentYear));
            if (this._stayOpen) {
                inst.rangeStart = this._daylightSavingAdjust(
                        new Date(inst.currentYear, inst.currentMonth, inst.currentDay));
                this._updateDatepicker(inst);
            }
            else if (rangeSelect) {
                inst.selectedDay = inst.currentDay = inst.rangeStart.getDate();
                inst.selectedMonth = inst.currentMonth = inst.rangeStart.getMonth();
                inst.selectedYear = inst.currentYear = inst.rangeStart.getFullYear();
                inst.rangeStart = null;
                if (inst.inline)
                    this._updateDatepicker(inst);
            }
        },

        /* Erase the input field and hide the date picker. */
        _clearDate: function(id) {
            var target = $(id);
            var inst = $.data(target[0], PROP_NAME);
            if (this._get(inst, 'mandatory'))
                return;
            this._stayOpen = false;
            inst.endDay = inst.endMonth = inst.endYear = inst.rangeStart = null;
            this._selectDate(target, '');
        },

        /* Update the input field with the selected date. */
        _selectDate: function(id, dateStr) {
            var target = $(id);
            var inst = $.data(target[0], PROP_NAME);
            dateStr = (dateStr != null ? dateStr : this._formatDate(inst));
            if (this._get(inst, 'rangeSelect') && dateStr)
                dateStr = (inst.rangeStart ? this._formatDate(inst, inst.rangeStart) :
                           dateStr) + this._get(inst, 'rangeSeparator') + dateStr;
            if (inst.input)
                inst.input.val(dateStr);
            this._updateAlternate(inst);
            var onSelect = this._get(inst, 'onSelect');
            if (onSelect)
                onSelect.apply((inst.input ? inst.input[0] : null), [dateStr, inst]);  // trigger custom callback
            else if (inst.input)
                inst.input.trigger('change'); // fire the change event
            if (inst.inline)
                this._updateDatepicker(inst);
            else if (!this._stayOpen) {
                this._hideDatepicker(null, this._get(inst, 'duration'));
                this._lastInput = inst.input[0];
                if (typeof(inst.input[0]) != 'object')
                    inst.input[0].focus(); // restore focus
                this._lastInput = null;
            }
        },

        /* Update any alternate field to synchronise with the main field. */
        _updateAlternate: function(inst) {
            var altField = this._get(inst, 'altField');
            if (altField) { // update alternate field too
                var altFormat = this._get(inst, 'altFormat');
                var date = this._getDate(inst);
                dateStr = (isArray(date) ? (!date[0] && !date[1] ? '' :
                                            this.formatDate(altFormat, date[0], this._getFormatConfig(inst)) +
                                            this._get(inst, 'rangeSeparator') + this.formatDate(
                                                    altFormat, date[1] || date[0], this._getFormatConfig(inst))) :
                           this.formatDate(altFormat, date, this._getFormatConfig(inst)));
                $(altField).each(function() {
                    $(this).val(dateStr);
                });
            }
        },

        /* Set as beforeShowDay function to prevent selection of weekends.
         @param  date  Date - the date to customise
         @return [boolean, string] - is this date selectable?, what is its CSS class? */
        noWeekends: function(date) {
            var day = date.getDay();
            return [(day > 0 && day < 6), ''];
        },

        /* Set as calculateWeek to determine the week of the year based on the ISO 8601 definition.
         @param  date  Date - the date to get the week for
         @return  number - the number of the week within the year that contains this date */
        iso8601Week: function(date) {
            var checkDate = new Date(date.getFullYear(), date.getMonth(), date.getDate());
            var firstMon = new Date(checkDate.getFullYear(), 1 - 1, 4); // First week always contains 4 Jan
            var firstDay = firstMon.getDay() || 7; // Day of week: Mon = 1, ..., Sun = 7
            firstMon.setDate(firstMon.getDate() + 1 - firstDay); // Preceding Monday
            if (firstDay < 4 && checkDate < firstMon) { // Adjust first three days in year if necessary
                checkDate.setDate(checkDate.getDate() - 3); // Generate for previous year
                return $.datepicker.iso8601Week(checkDate);
            } else if (checkDate > new Date(checkDate.getFullYear(), 12 - 1, 28)) { // Check last three days in year
                firstDay = new Date(checkDate.getFullYear() + 1, 1 - 1, 4).getDay() || 7;
                if (firstDay > 4 && (checkDate.getDay() || 7) < firstDay - 3) { // Adjust if necessary
                    checkDate.setDate(checkDate.getDate() + 3); // Generate for next year
                    return $.datepicker.iso8601Week(checkDate);
                }
            }
            return Math.floor(((checkDate - firstMon) / 86400000) / 7) + 1; // Weeks to given date
        },

        /* Provide status text for a particular date.
         @param  date  the date to get the status for
         @param  inst  the current datepicker instance
         @return  the status display text for this date */
        dateStatus: function(date, inst) {
            return $.datepicker.formatDate($.datepicker._get(inst, 'dateStatus'),
                    date, $.datepicker._getFormatConfig(inst));
        },

        /* Parse a string value into a date object.
         See formatDate below for the possible formats.

         @param  format    string - the expected format of the date
         @param  value     string - the date in the above format
         @param  settings  Object - attributes include:
         shortYearCutoff  number - the cutoff year for determining the century (optional)
         dayNamesShort    string[7] - abbreviated names of the days from Sunday (optional)
         dayNames         string[7] - names of the days from Sunday (optional)
         monthNamesShort  string[12] - abbreviated names of the months (optional)
         monthNames       string[12] - names of the months (optional)
         @return  Date - the extracted date value or null if value is blank */
        parseDate: function (format, value, settings) {
            if (format == null || value == null)
                throw 'Invalid arguments';
            value = (typeof value == 'object' ? value.toString() : value + '');
            if (value == '')
                return null;
            var shortYearCutoff = (settings ? settings.shortYearCutoff : null) || this._defaults.shortYearCutoff;
            var dayNamesShort = (settings ? settings.dayNamesShort : null) || this._defaults.dayNamesShort;
            var dayNames = (settings ? settings.dayNames : null) || this._defaults.dayNames;
            var monthNamesShort = (settings ? settings.monthNamesShort : null) || this._defaults.monthNamesShort;
            var monthNames = (settings ? settings.monthNames : null) || this._defaults.monthNames;
            var year = -1;
            var month = -1;
            var day = -1;
            var literal = false;
            // Check whether a format character is doubled
            var lookAhead = function(match) {
                var matches = (iFormat + 1 < format.length && format.charAt(iFormat + 1) == match);
                if (matches)
                    iFormat++;
                return matches;
            };
            // Extract a number from the string value
            var getNumber = function(match) {
                lookAhead(match);
                var origSize = (match == '@' ? 14 : (match == 'y' ? 4 : 2));
                var size = origSize;
                var num = 0;
                while (size > 0 && iValue < value.length &&
                       value.charAt(iValue) >= '0' && value.charAt(iValue) <= '9') {
                    num = num * 10 + (value.charAt(iValue++) - 0);
                    size--;
                }
                if (size == origSize)
                    throw 'Missing number at position ' + iValue;
                return num;
            };
            // Extract a name from the string value and convert to an index
            var getName = function(match, shortNames, longNames) {
                var names = (lookAhead(match) ? longNames : shortNames);
                var size = 0;
                for (var j = 0; j < names.length; j++)
                    size = Math.max(size, names[j].length);
                var name = '';
                var iInit = iValue;
                while (size > 0 && iValue < value.length) {
                    name += value.charAt(iValue++);
                    for (var i = 0; i < names.length; i++)
                        if (name == names[i])
                            return i + 1;
                    size--;
                }
                throw 'Unknown name at position ' + iInit;
            };
            // Confirm that a literal character matches the string value
            var checkLiteral = function() {
                if (value.charAt(iValue) != format.charAt(iFormat))
                    throw 'Unexpected literal at position ' + iValue;
                iValue++;
            };
            var iValue = 0;
            for (var iFormat = 0; iFormat < format.length; iFormat++) {
                if (literal)
                    if (format.charAt(iFormat) == "'" && !lookAhead("'"))
                        literal = false;
                    else
                        checkLiteral();
                else
                    switch (format.charAt(iFormat)) {
                        case 'd':
                            day = getNumber('d');
                            break;
                        case 'D':
                            getName('D', dayNamesShort, dayNames);
                            break;
                        case 'm':
                            month = getNumber('m');
                            break;
                        case 'M':
                            month = getName('M', monthNamesShort, monthNames);
                            break;
                        case 'y':
                            year = getNumber('y');
                            break;
                        case '@':
                            var date = new Date(getNumber('@'));
                            year = date.getFullYear();
                            month = date.getMonth() + 1;
                            day = date.getDate();
                            break;
                        case "'":
                            if (lookAhead("'"))
                                checkLiteral();
                            else
                                literal = true;
                            break;
                        default:
                            checkLiteral();
                    }
            }
            if (year < 100)
                year += new Date().getFullYear() - new Date().getFullYear() % 100 +
                        (year <= shortYearCutoff ? 0 : -100);
            var date = this._daylightSavingAdjust(new Date(year, month - 1, day));
            if (date.getFullYear() != year || date.getMonth() + 1 != month || date.getDate() != day)
                throw 'Invalid date'; // E.g. 31/02/*
            return date;
        },

        /* Standard date formats. */
        ATOM: 'yy-mm-dd', // RFC 3339 (ISO 8601)
        COOKIE: 'D, dd M yy',
        ISO_8601: 'yy-mm-dd',
        RFC_822: 'D, d M y',
        RFC_850: 'DD, dd-M-y',
        RFC_1036: 'D, d M y',
        RFC_1123: 'D, d M yy',
        RFC_2822: 'D, d M yy',
        RSS: 'D, d M y', // RFC 822
        TIMESTAMP: '@',
        W3C: 'yy-mm-dd', // ISO 8601

        /* Format a date object into a string value.
         The format can be combinations of the following:
         d  - day of month (no leading zero)
         dd - day of month (two digit)
         D  - day name short
         DD - day name long
         m  - month of year (no leading zero)
         mm - month of year (two digit)
         M  - month name short
         MM - month name long
         y  - year (two digit)
         yy - year (four digit)
         @ - Unix timestamp (ms since 01/01/1970)
         '...' - literal text
         '' - single quote

         @param  format    string - the desired format of the date
         @param  date      Date - the date value to format
         @param  settings  Object - attributes include:
         dayNamesShort    string[7] - abbreviated names of the days from Sunday (optional)
         dayNames         string[7] - names of the days from Sunday (optional)
         monthNamesShort  string[12] - abbreviated names of the months (optional)
         monthNames       string[12] - names of the months (optional)
         @return  string - the date in the above format */
        formatDate: function (format, date, settings) {
            if (!date)
                return '';
            var dayNamesShort = (settings ? settings.dayNamesShort : null) || this._defaults.dayNamesShort;
            var dayNames = (settings ? settings.dayNames : null) || this._defaults.dayNames;
            var monthNamesShort = (settings ? settings.monthNamesShort : null) || this._defaults.monthNamesShort;
            var monthNames = (settings ? settings.monthNames : null) || this._defaults.monthNames;
            // Check whether a format character is doubled
            var lookAhead = function(match) {
                var matches = (iFormat + 1 < format.length && format.charAt(iFormat + 1) == match);
                if (matches)
                    iFormat++;
                return matches;
            };
            // Format a number, with leading zero if necessary
            var formatNumber = function(match, value) {
                return (lookAhead(match) && value < 10 ? '0' : '') + value;
            };
            // Format a name, short or long as requested
            var formatName = function(match, value, shortNames, longNames) {
                return (lookAhead(match) ? longNames[value] : shortNames[value]);
            };
            var output = '';
            var literal = false;
            if (date)
                for (var iFormat = 0; iFormat < format.length; iFormat++) {
                    if (literal)
                        if (format.charAt(iFormat) == "'" && !lookAhead("'"))
                            literal = false;
                        else
                            output += format.charAt(iFormat);
                    else
                        switch (format.charAt(iFormat)) {
                            case 'd':
                                output += formatNumber('d', date.getDate());
                                break;
                            case 'D':
                                output += formatName('D', date.getDay(), dayNamesShort, dayNames);
                                break;
                            case 'm':
                                output += formatNumber('m', date.getMonth() + 1);
                                break;
                            case 'M':
                                output += formatName('M', date.getMonth(), monthNamesShort, monthNames);
                                break;
                            case 'y':
                                output += (lookAhead('y') ? date.getFullYear() :
                                           (date.getYear() % 100 < 10 ? '0' : '') + date.getYear() % 100);
                                break;
                            case '@':
                                output += date.getTime();
                                break;
                            case "'":
                                if (lookAhead("'"))
                                    output += "'";
                                else
                                    literal = true;
                                break;
                            default:
                                output += format.charAt(iFormat);
                        }
                }
            return output;
        },

        /* Extract all possible characters from the date format. */
        _possibleChars: function (format) {
            var chars = '';
            var literal = false;
            for (var iFormat = 0; iFormat < format.length; iFormat++)
                if (literal)
                    if (format.charAt(iFormat) == "'" && !lookAhead("'"))
                        literal = false;
                    else
                        chars += format.charAt(iFormat);
                else
                    switch (format.charAt(iFormat)) {
                        case 'd': case 'm': case 'y': case '@':
                        chars += '0123456789';
                        break;
                        case 'D': case 'M':
                        return null; // Accept anything
                        case "'":
                            if (lookAhead("'"))
                                chars += "'";
                            else
                                literal = true;
                            break;
                        default:
                            chars += format.charAt(iFormat);
                    }
            return chars;
        },

        /* Get a setting value, defaulting if necessary. */
        _get: function(inst, name) {
            return inst.settings[name] !== undefined ?
                   inst.settings[name] : this._defaults[name];
        },

        /* Parse existing date and initialise date picker. */
        _setDateFromField: function(inst) {
            var dateFormat = this._get(inst, 'dateFormat');
            var dates = inst.input ? inst.input.val().split(this._get(inst, 'rangeSeparator')) : null;
            inst.endDay = inst.endMonth = inst.endYear = null;
            var date = defaultDate = this._getDefaultDate(inst);
            if (dates.length > 0) {
                var settings = this._getFormatConfig(inst);
                if (dates.length > 1) {
                    date = this.parseDate(dateFormat, dates[1], settings) || defaultDate;
                    inst.endDay = date.getDate();
                    inst.endMonth = date.getMonth();
                    inst.endYear = date.getFullYear();
                }
                try {
                    date = this.parseDate(dateFormat, dates[0], settings) || defaultDate;
                } catch (e) {
                    this.log(e);
                    date = defaultDate;
                }
            }
            inst.selectedDay = date.getDate();
            inst.drawMonth = inst.selectedMonth = date.getMonth();
            inst.drawYear = inst.selectedYear = date.getFullYear();
            inst.currentDay = (dates[0] ? date.getDate() : 0);
            inst.currentMonth = (dates[0] ? date.getMonth() : 0);
            inst.currentYear = (dates[0] ? date.getFullYear() : 0);
            this._adjustInstDate(inst);
        },

        /* Retrieve the default date shown on opening. */
        _getDefaultDate: function(inst) {
            var date = this._determineDate(this._get(inst, 'defaultDate'), new Date());
            var minDate = this._getMinMaxDate(inst, 'min', true);
            var maxDate = this._getMinMaxDate(inst, 'max');
            date = (minDate && date < minDate ? minDate : date);
            date = (maxDate && date > maxDate ? maxDate : date);
            return date;
        },

        /* A date may be specified as an exact value or a relative one. */
        _determineDate: function(date, defaultDate) {
            var offsetNumeric = function(offset) {
                var date = new Date();
                date.setDate(date.getDate() + offset);
                return date;
            };
            var offsetString = function(offset, getDaysInMonth) {
                var date = new Date();
                var year = date.getFullYear();
                var month = date.getMonth();
                var day = date.getDate();
                var pattern = /([+-]?[0-9]+)\s*(d|D|w|W|m|M|y|Y)?/g;
                var matches = pattern.exec(offset);
                while (matches) {
                    switch (matches[2] || 'd') {
                        case 'd' : case 'D' :
                        day += (matches[1] - 0); break;
                        case 'w' : case 'W' :
                        day += (matches[1] * 7); break;
                        case 'm' : case 'M' :
                        month += (matches[1] - 0);
                        day = Math.min(day, getDaysInMonth(year, month));
                        break;
                        case 'y': case 'Y' :
                        year += (matches[1] - 0);
                        day = Math.min(day, getDaysInMonth(year, month));
                        break;
                    }
                    matches = pattern.exec(offset);
                }
                return new Date(year, month, day);
            };
            date = (date == null ? defaultDate :
                    (typeof date == 'string' ? offsetString(date, this._getDaysInMonth) :
                     (typeof date == 'number' ? (isNaN(date) ? defaultDate : offsetNumeric(date)) : date)));
            date = (date && date.toString() == 'Invalid Date' ? defaultDate : date);
            if (date) {
                date.setHours(0);
                date.setMinutes(0);
                date.setSeconds(0);
                date.setMilliseconds(0);
            }
            return this._daylightSavingAdjust(date);
        },

        /* Handle switch to/from daylight saving.
         Hours may be non-zero on daylight saving cut-over:
         > 12 when midnight changeover, but then cannot generate
         midnight datetime, so jump to 1AM, otherwise reset.
         @param  date  (Date) the date to check
         @return  (Date) the corrected date */
        _daylightSavingAdjust: function(date) {
            if (!date) return null;
            date.setHours(date.getHours() > 12 ? date.getHours() + 2 : 0);
            return date;
        },

        /* Set the date(s) directly. */
        _setDate: function(inst, date, endDate) {
            var clear = !(date);
            date = this._determineDate(date, new Date());
            inst.selectedDay = inst.currentDay = date.getDate();
            inst.drawMonth = inst.selectedMonth = inst.currentMonth = date.getMonth();
            inst.drawYear = inst.selectedYear = inst.currentYear = date.getFullYear();
            if (this._get(inst, 'rangeSelect')) {
                if (endDate) {
                    endDate = this._determineDate(endDate, null);
                    inst.endDay = endDate.getDate();
                    inst.endMonth = endDate.getMonth();
                    inst.endYear = endDate.getFullYear();
                } else {
                    inst.endDay = inst.currentDay;
                    inst.endMonth = inst.currentMonth;
                    inst.endYear = inst.currentYear;
                }
            }
            this._adjustInstDate(inst);
            if (inst.input)
                inst.input.val(clear ? '' : this._formatDate(inst) +
                                            (!this._get(inst, 'rangeSelect') ? '' : this._get(inst, 'rangeSeparator') +
                                                                                    this._formatDate(inst, inst.endDay, inst.endMonth, inst.endYear)));
        },

        /* Retrieve the date(s) directly. */
        _getDate: function(inst) {
            var startDate = (!inst.currentYear || (inst.input && inst.input.val() == '') ? null :
                             this._daylightSavingAdjust(new Date(
                                     inst.currentYear, inst.currentMonth, inst.currentDay)));
            if (this._get(inst, 'rangeSelect')) {
                return [inst.rangeStart || startDate,
                    (!inst.endYear ? inst.rangeStart || startDate :
                     this._daylightSavingAdjust(new Date(inst.endYear, inst.endMonth, inst.endDay)))];
            } else
                return startDate;
        },

        /* Generate the HTML for the current state of the date picker. */
        _generateDatepicker: function(inst) {
            var today = new Date();
            today = this._daylightSavingAdjust(
                    new Date(today.getFullYear(), today.getMonth(), today.getDate())); // clear time
            var showStatus = this._get(inst, 'showStatus');
            var isRTL = this._get(inst, 'isRTL');
            // build the date picker HTML
            var clear = (this._get(inst, 'mandatory') ? '' :
                         '<div class="ui-datepicker-clear"><a onclick="jQuery.datepicker._clearDate(\'#' + inst.id + '\');"' +
                         (showStatus ? this._addStatus(inst, this._get(inst, 'clearStatus') || '&#xa0;') : '') + '>' +
                         this._get(inst, 'clearText') + '</a></div>');
            var controls = '<div class="ui-datepicker-control">' + (isRTL ? '' : clear) +
                           '<div class="ui-datepicker-close"><a onclick="jQuery.datepicker._hideDatepicker();"' +
                           (showStatus ? this._addStatus(inst, this._get(inst, 'closeStatus') || '&#xa0;') : '') + '>' +
                           this._get(inst, 'closeText') + '</a></div>' + (isRTL ? clear : '') + '</div>';
            var prompt = this._get(inst, 'prompt');
            var closeAtTop = this._get(inst, 'closeAtTop');
            var hideIfNoPrevNext = this._get(inst, 'hideIfNoPrevNext');
            var navigationAsDateFormat = this._get(inst, 'navigationAsDateFormat');
            var numMonths = this._getNumberOfMonths(inst);
            var stepMonths = this._get(inst, 'stepMonths');
            var isMultiMonth = (numMonths[0] != 1 || numMonths[1] != 1);
            var currentDate = this._daylightSavingAdjust((!inst.currentDay ? new Date(9999, 9, 9) :
                                                          new Date(inst.currentYear, inst.currentMonth, inst.currentDay)));
            var minDate = this._getMinMaxDate(inst, 'min', true);
            var maxDate = this._getMinMaxDate(inst, 'max');
            var drawMonth = inst.drawMonth;
            var drawYear = inst.drawYear;
            if (maxDate) {
                var maxDraw = this._daylightSavingAdjust(new Date(maxDate.getFullYear(),
                        maxDate.getMonth() - numMonths[1] + 1, maxDate.getDate()));
                maxDraw = (minDate && maxDraw < minDate ? minDate : maxDraw);
                while (this._daylightSavingAdjust(new Date(drawYear, drawMonth, 1)) > maxDraw) {
                    drawMonth--;
                    if (drawMonth < 0) {
                        drawMonth = 11;
                        drawYear--;
                    }
                }
            }
            // controls and links
            var prevText = this._get(inst, 'prevText');
            prevText = (!navigationAsDateFormat ? prevText : this.formatDate(prevText,
                    this._daylightSavingAdjust(new Date(drawYear, drawMonth - stepMonths, 1)),
                    this._getFormatConfig(inst)));
            var prev = '<div class="ui-datepicker-prev">' + (this._canAdjustMonth(inst, -1, drawYear, drawMonth) ?
                                                             '<a onclick="jQuery.datepicker._adjustDate(\'#' + inst.id + '\', -' + stepMonths + ', \'M\');"' +
                                                             (showStatus ? this._addStatus(inst, this._get(inst, 'prevStatus') || '&#xa0;') : '') + '>' + prevText + '</a>' :
                                                             (hideIfNoPrevNext ? '' : '<label>' + prevText + '</label>')) + '</div>';
            var nextText = this._get(inst, 'nextText');
            nextText = (!navigationAsDateFormat ? nextText : this.formatDate(nextText,
                    this._daylightSavingAdjust(new Date(drawYear, drawMonth + stepMonths, 1)),
                    this._getFormatConfig(inst)));
            var next = '<div class="ui-datepicker-next">' + (this._canAdjustMonth(inst, +1, drawYear, drawMonth) ?
                                                             '<a onclick="jQuery.datepicker._adjustDate(\'#' + inst.id + '\', +' + stepMonths + ', \'M\');"' +
                                                             (showStatus ? this._addStatus(inst, this._get(inst, 'nextStatus') || '&#xa0;') : '') + '>' + nextText + '</a>' :
                                                             (hideIfNoPrevNext ? '' : '<label>' + nextText + '</label>')) + '</div>';
            var currentText = this._get(inst, 'currentText');
            currentText = (!navigationAsDateFormat ? currentText : this.formatDate(
                    currentText, today, this._getFormatConfig(inst)));
            var html = (prompt ? '<div class="' + this._promptClass + '">' + prompt + '</div>' : '') +
                       (closeAtTop && !inst.inline ? controls : '') +
                       '<div class="ui-datepicker-links">' + (isRTL ? next : prev) +
                       (this._isInRange(inst, (this._get(inst, 'gotoCurrent') && inst.currentDay ?
                                               currentDate : today)) ? '<div class="ui-datepicker-current">' +
                                                                       '<a onclick="jQuery.datepicker._gotoToday(\'#' + inst.id + '\');"' +
                                                                       (showStatus ? this._addStatus(inst, this._get(inst, 'currentStatus') || '&#xa0;') : '') + '>' +
                                                                       currentText + '</a></div>' : '') + (isRTL ? prev : next) + '</div>';
            var firstDay = this._get(inst, 'firstDay');
            var changeFirstDay = this._get(inst, 'changeFirstDay');
            var dayNames = this._get(inst, 'dayNames');
            var dayNamesShort = this._get(inst, 'dayNamesShort');
            var dayNamesMin = this._get(inst, 'dayNamesMin');
            var monthNames = this._get(inst, 'monthNames');
            var beforeShowDay = this._get(inst, 'beforeShowDay');
            var highlightWeek = this._get(inst, 'highlightWeek');
            var showOtherMonths = this._get(inst, 'showOtherMonths');
            var showWeeks = this._get(inst, 'showWeeks');
            var calculateWeek = this._get(inst, 'calculateWeek') || this.iso8601Week;
            var status = (showStatus ? this._get(inst, 'dayStatus') || '&#xa0;' : '');
            var dateStatus = this._get(inst, 'statusForDate') || this.dateStatus;
            var endDate = inst.endDay ? this._daylightSavingAdjust(
                    new Date(inst.endYear, inst.endMonth, inst.endDay)) : currentDate;
            for (var row = 0; row < numMonths[0]; row++)
                for (var col = 0; col < numMonths[1]; col++) {
                    var selectedDate = this._daylightSavingAdjust(new Date(drawYear, drawMonth, inst.selectedDay));
                    html += '<div class="ui-datepicker-one-month' + (col == 0 ? ' ui-datepicker-new-row' : '') + '">' +
                            this._generateMonthYearHeader(inst, drawMonth, drawYear, minDate, maxDate,
                                    selectedDate, row > 0 || col > 0, showStatus, monthNames) + // draw month headers
                            '<table class="ui-datepicker" cellpadding="0" cellspacing="0"><thead>' +
                            '<tr class="ui-datepicker-title-row">' +
                            (showWeeks ? '<td>' + this._get(inst, 'weekHeader') + '</td>' : '');
                    for (var dow = 0; dow < 7; dow++) { // days of the week
                        var day = (dow + firstDay) % 7;
                        var dayStatus = (status.indexOf('DD') > -1 ? status.replace(/DD/, dayNames[day]) :
                                         status.replace(/D/, dayNamesShort[day]));
                        html += '<td' + ((dow + firstDay + 6) % 7 >= 5 ? ' class="ui-datepicker-week-end-cell"' : '') + '>' +
                                (!changeFirstDay ? '<span' :
                                 '<a onclick="jQuery.datepicker._changeFirstDay(\'#' + inst.id + '\', ' + day + ');"') +
                                (showStatus ? this._addStatus(inst, dayStatus) : '') + ' title="' + dayNames[day] + '">' +
                                dayNamesMin[day] + (changeFirstDay ? '</a>' : '</span>') + '</td>';
                    }
                    html += '</tr></thead><tbody>';
                    var daysInMonth = this._getDaysInMonth(drawYear, drawMonth);
                    if (drawYear == inst.selectedYear && drawMonth == inst.selectedMonth)
                        inst.selectedDay = Math.min(inst.selectedDay, daysInMonth);
                    var leadDays = (this._getFirstDayOfMonth(drawYear, drawMonth) - firstDay + 7) % 7;
                    var numRows = (isMultiMonth ? 6 : Math.ceil((leadDays + daysInMonth) / 7)); // calculate the number of rows to generate
                    var printDate = this._daylightSavingAdjust(new Date(drawYear, drawMonth, 1 - leadDays));
                    for (var dRow = 0; dRow < numRows; dRow++) { // create date picker rows
                        html += '<tr class="ui-datepicker-days-row">' +
                                (showWeeks ? '<td class="ui-datepicker-week-col">' + calculateWeek(printDate) + '</td>' : '');
                        for (var dow = 0; dow < 7; dow++) { // create date picker days
                            var daySettings = (beforeShowDay ?
                                               beforeShowDay.apply((inst.input ? inst.input[0] : null), [printDate]) : [true, '']);
                            var otherMonth = (printDate.getMonth() != drawMonth);
                            var unselectable = otherMonth || !daySettings[0] ||
                                               (minDate && printDate < minDate) || (maxDate && printDate > maxDate);
                            html += '<td class="ui-datepicker-days-cell' +
                                    ((dow + firstDay + 6) % 7 >= 5 ? ' ui-datepicker-week-end-cell' : '') + // highlight weekends
                                    (otherMonth ? ' ui-datepicker-otherMonth' : '') + // highlight days from other months
                                    (printDate.getTime() == selectedDate.getTime() && drawMonth == inst.selectedMonth ?
                                     ' ui-datepicker-days-cell-over' : '') + // highlight selected day
                                    (unselectable ? ' ' + this._unselectableClass : '') + // highlight unselectable days
                                    (otherMonth && !showOtherMonths ? '' : ' ' + daySettings[1] + // highlight custom dates
                                                                           (printDate.getTime() >= currentDate.getTime() && printDate.getTime() <= endDate.getTime() ? // in current range
                                                                            ' ' + this._currentClass : '') + // highlight selected day
                                                                           (printDate.getTime() == today.getTime() ? ' ui-datepicker-today' : '')) + '"' + // highlight today (if different)
                                    ((!otherMonth || showOtherMonths) && daySettings[2] ? ' title="' + daySettings[2] + '"' : '') + // cell title
                                    (unselectable ? (highlightWeek ? ' onmouseover="jQuery(this).parent().addClass(\'ui-datepicker-week-over\');"' + // highlight selection week
                                                                     ' onmouseout="jQuery(this).parent().removeClass(\'ui-datepicker-week-over\');"' : '') : // unhighlight selection week
                                     ' onmouseover="jQuery(this).addClass(\'ui-datepicker-days-cell-over\')' + // highlight selection
                                     (highlightWeek ? '.parent().addClass(\'ui-datepicker-week-over\')' : '') + ';' + // highlight selection week
                                     (!showStatus || (otherMonth && !showOtherMonths) ? '' : 'jQuery(\'#ui-datepicker-status-' +
                                                                                             inst.id + '\').html(\'' + (dateStatus.apply((inst.input ? inst.input[0] : null),
                                             [printDate, inst]) || '&#xa0;') + '\');') + '"' +
                                     ' onmouseout="jQuery(this).removeClass(\'ui-datepicker-days-cell-over\')' + // unhighlight selection
                                     (highlightWeek ? '.parent().removeClass(\'ui-datepicker-week-over\')' : '') + ';' + // unhighlight selection week
                                     (!showStatus || (otherMonth && !showOtherMonths) ? '' : 'jQuery(\'#ui-datepicker-status-' +
                                                                                             inst.id + '\').html(\'&#xa0;\');') + '" onclick="jQuery.datepicker._selectDay(\'#' +
                                     inst.id + '\',' + drawMonth + ',' + drawYear + ', this);"') + '>' + // actions
                                    (otherMonth ? (showOtherMonths ? printDate.getDate() : '&#xa0;') : // display for other months
                                     (unselectable ? printDate.getDate() : '<a>' + printDate.getDate() + '</a>')) + '</td>'; // display for this month
                            printDate.setDate(printDate.getDate() + 1);
                            printDate = this._daylightSavingAdjust(printDate);
                        }
                        html += '</tr>';
                    }
                    drawMonth++;
                    if (drawMonth > 11) {
                        drawMonth = 0;
                        drawYear++;
                    }
                    html += '</tbody></table></div>';
                }
            html += (showStatus ? '<div style="clear: both;"></div><div id="ui-datepicker-status-' + inst.id +
                                  '" class="ui-datepicker-status">' + (this._get(inst, 'initStatus') || '&#xa0;') + '</div>' : '') +
                    (!closeAtTop && !inst.inline ? controls : '') +
                    '<div style="clear: both;"></div>' +
                    ($.browser.msie && parseInt($.browser.version) < 7 && !inst.inline ?
                     '<iframe src="javascript:false;" class="ui-datepicker-cover"></iframe>' : '');
            return html;
        },

        /* Generate the month and year header. */
        _generateMonthYearHeader: function(inst, drawMonth, drawYear, minDate, maxDate,
                                           selectedDate, secondary, showStatus, monthNames) {
            minDate = (inst.rangeStart && minDate && selectedDate < minDate ? selectedDate : minDate);
            var html = '<div class="ui-datepicker-header">';
            // month selection
            if (secondary || !this._get(inst, 'changeMonth'))
                html += monthNames[drawMonth] + '&#xa0;';
            else {
                var inMinYear = (minDate && minDate.getFullYear() == drawYear);
                var inMaxYear = (maxDate && maxDate.getFullYear() == drawYear);
                html += '<select class="ui-datepicker-new-month" ' +
                        'onchange="jQuery.datepicker._selectMonthYear(\'#' + inst.id + '\', this, \'M\');" ' +
                        'onclick="jQuery.datepicker._clickMonthYear(\'#' + inst.id + '\');"' +
                        (showStatus ? this._addStatus(inst, this._get(inst, 'monthStatus') || '&#xa0;') : '') + '>';
                for (var month = 0; month < 12; month++) {
                    if ((!inMinYear || month >= minDate.getMonth()) &&
                        (!inMaxYear || month <= maxDate.getMonth()))
                        html += '<option value="' + month + '"' +
                                (month == drawMonth ? ' selected="selected"' : '') +
                                '>' + monthNames[month] + '</option>';
                }
                html += '</select>';
            }
            // year selection
            if (secondary || !this._get(inst, 'changeYear'))
                html += drawYear;
            else {
                // determine range of years to display
                var years = this._get(inst, 'yearRange').split(':');
                var year = 0;
                var endYear = 0;
                if (years.length != 2) {
                    year = drawYear - 10;
                    endYear = drawYear + 10;
                } else if (years[0].charAt(0) == '+' || years[0].charAt(0) == '-') {
                    year = endYear = new Date().getFullYear();
                    year += parseInt(years[0], 10);
                    endYear += parseInt(years[1], 10);
                } else {
                    year = parseInt(years[0], 10);
                    endYear = parseInt(years[1], 10);
                }
                year = (minDate ? Math.max(year, minDate.getFullYear()) : year);
                endYear = (maxDate ? Math.min(endYear, maxDate.getFullYear()) : endYear);
                html += '<select class="ui-datepicker-new-year" ' +
                        'onchange="jQuery.datepicker._selectMonthYear(\'#' + inst.id + '\', this, \'Y\');" ' +
                        'onclick="jQuery.datepicker._clickMonthYear(\'#' + inst.id + '\');"' +
                        (showStatus ? this._addStatus(inst, this._get(inst, 'yearStatus') || '&#xa0;') : '') + '>';
                for (; year <= endYear; year++) {
                    html += '<option value="' + year + '"' +
                            (year == drawYear ? ' selected="selected"' : '') +
                            '>' + year + '</option>';
                }
                html += '</select>';
            }
            html += '</div>'; // Close datepicker_header
            return html;
        },

        /* Provide code to set and clear the status panel. */
        _addStatus: function(inst, text) {
            return ' onmouseover="jQuery(\'#ui-datepicker-status-' + inst.id + '\').html(\'' + text + '\');" ' +
                   'onmouseout="jQuery(\'#ui-datepicker-status-' + inst.id + '\').html(\'&#xa0;\');"';
        },

        /* Adjust one of the date sub-fields. */
        _adjustInstDate: function(inst, offset, period) {
            var year = inst.drawYear + (period == 'Y' ? offset : 0);
            var month = inst.drawMonth + (period == 'M' ? offset : 0);
            var day = Math.min(inst.selectedDay, this._getDaysInMonth(year, month)) +
                      (period == 'D' ? offset : 0);
            var date = this._daylightSavingAdjust(new Date(year, month, day));
            // ensure it is within the bounds set
            var minDate = this._getMinMaxDate(inst, 'min', true);
            var maxDate = this._getMinMaxDate(inst, 'max');
            date = (minDate && date < minDate ? minDate : date);
            date = (maxDate && date > maxDate ? maxDate : date);
            inst.selectedDay = date.getDate();
            inst.drawMonth = inst.selectedMonth = date.getMonth();
            inst.drawYear = inst.selectedYear = date.getFullYear();
            if (period == 'M' || period == 'Y')
                this._notifyChange(inst);
        },

        /* Notify change of month/year. */
        _notifyChange: function(inst) {
            var onChange = this._get(inst, 'onChangeMonthYear');
            if (onChange)
                onChange.apply((inst.input ? inst.input[0] : null),
                        [new Date(inst.selectedYear, inst.selectedMonth, 1), inst]);
        },

        /* Determine the number of months to show. */
        _getNumberOfMonths: function(inst) {
            var numMonths = this._get(inst, 'numberOfMonths');
            return (numMonths == null ? [1, 1] : (typeof numMonths == 'number' ? [1, numMonths] : numMonths));
        },

        /* Determine the current maximum date - ensure no time components are set - may be overridden for a range. */
        _getMinMaxDate: function(inst, minMax, checkRange) {
            var date = this._determineDate(this._get(inst, minMax + 'Date'), null);
            return (!checkRange || !inst.rangeStart ? date :
                    (!date || inst.rangeStart > date ? inst.rangeStart : date));
        },

        /* Find the number of days in a given month. */
        _getDaysInMonth: function(year, month) {
            return 32 - new Date(year, month, 32).getDate();
        },

        /* Find the day of the week of the first of a month. */
        _getFirstDayOfMonth: function(year, month) {
            return new Date(year, month, 1).getDay();
        },

        /* Determines if we should allow a "next/prev" month display change. */
        _canAdjustMonth: function(inst, offset, curYear, curMonth) {
            var numMonths = this._getNumberOfMonths(inst);
            var date = this._daylightSavingAdjust(new Date(
                    curYear, curMonth + (offset < 0 ? offset : numMonths[1]), 1));
            if (offset < 0)
                date.setDate(this._getDaysInMonth(date.getFullYear(), date.getMonth()));
            return this._isInRange(inst, date);
        },

        /* Is the given date in the accepted range? */
        _isInRange: function(inst, date) {
            // during range selection, use minimum of selected date and range start
            var newMinDate = (!inst.rangeStart ? null : this._daylightSavingAdjust(
                    new Date(inst.selectedYear, inst.selectedMonth, inst.selectedDay)));
            newMinDate = (newMinDate && inst.rangeStart < newMinDate ? inst.rangeStart : newMinDate);
            var minDate = newMinDate || this._getMinMaxDate(inst, 'min');
            var maxDate = this._getMinMaxDate(inst, 'max');
            return ((!minDate || date >= minDate) && (!maxDate || date <= maxDate));
        },

        /* Provide the configuration settings for formatting/parsing. */
        _getFormatConfig: function(inst) {
            var shortYearCutoff = this._get(inst, 'shortYearCutoff');
            shortYearCutoff = (typeof shortYearCutoff != 'string' ? shortYearCutoff :
                               new Date().getFullYear() % 100 + parseInt(shortYearCutoff, 10));
            return {shortYearCutoff: shortYearCutoff,
                dayNamesShort: this._get(inst, 'dayNamesShort'), dayNames: this._get(inst, 'dayNames'),
                monthNamesShort: this._get(inst, 'monthNamesShort'), monthNames: this._get(inst, 'monthNames')};
        },

        /* Format the given date for display. */
        _formatDate: function(inst, day, month, year) {
            if (!day) {
                inst.currentDay = inst.selectedDay;
                inst.currentMonth = inst.selectedMonth;
                inst.currentYear = inst.selectedYear;
            }
            var date = (day ? (typeof day == 'object' ? day :
                               this._daylightSavingAdjust(new Date(year, month, day))) :
                        this._daylightSavingAdjust(new Date(inst.currentYear, inst.currentMonth, inst.currentDay)));
            return this.formatDate(this._get(inst, 'dateFormat'), date, this._getFormatConfig(inst));
        }
    });

    /* jQuery extend now ignores nulls! */
    function extendRemove(target, props) {
        $.extend(target, props);
        for (var name in props)
            if (props[name] == null || props[name] == undefined)
                target[name] = props[name];
        return target;
    }
    ;

    /* Determine whether an object is an array. */
    function isArray(a) {
        return (a && (($.browser.safari && typeof a == 'object' && a.length) ||
                      (a.constructor && a.constructor.toString().match(/\Array\(\)/))));
    }
    ;

    /* Invoke the datepicker functionality.
     @param  options  string - a command, optionally followed by additional parameters or
     Object - settings for attaching new datepicker functionality
     @return  jQuery object */
    $.fn.datepicker = function(options) {
        var otherArgs = Array.prototype.slice.call(arguments, 1);
        if (typeof options == 'string' && (options == 'isDisabled' || options == 'getDate'))
            return $.datepicker['_' + options + 'Datepicker'].
                    apply($.datepicker, [this[0]].concat(otherArgs));
        return this.each(function() {
            typeof options == 'string' ?
            $.datepicker['_' + options + 'Datepicker'].
                    apply($.datepicker, [this].concat(otherArgs)) :
            $.datepicker._attachDatepicker(this, options);
        });
    };

    $.datepicker = new Datepicker(); // singleton instance

    /* Initialise the date picker. */
    $(document).ready(function() {
        $(document.body).append($.datepicker.dpDiv).
                mousedown($.datepicker._checkExternalClick);
    });

})(jQuery);
